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JOURNAL OF MOSQUITO RESEARCH
72
consider it from a mechanistic point of view, and to
discuss potential consequences of the integument surface
in the predator-prey relationships by using the LC
50
of
the methanol extract of
Matricharia chamomella
has
been identified in the present study alone for periods of
6 hours, 12 hours, 24 hours and 48 hours.
1 Results and Discussion
Insect exoskeletons, called cuticles, can stop chemical
and physical attack while also providing structure for
the insect's muscles and wings. The remarkable
material is very thin and has a low density. It can also
vary its properties, from rigid along the insect's body
segments and wings to elastic along its limb joints.
Insect cuticle is a composite made up of layers of
chitin, which is a polysaccharide polymer, and protein
organized in a laminar, plywood-like structure.
Mechanical and chemical interactions between these
materials provide the exoskeleton with unique
mechanical and chemical properties. The cuticle
consists of a relatively soft and colourless endocuticle,
hardened and darkened in its outer part in some places
to form a rigid exocuticle, and a complex epicuticle
made up of several layers.
Development of resistance among target insects and
concern for environmental pollution limit the use of
chemical insecticides. Biological control is an
important component of integrated vector control
strategy and is being practiced in many countries to
control mosquitoes (Fraenkel and Rudall, 1940;
Vincent and Ablett, 1988). However, biocontrol
agents effective against adult mosquitoes are limited,
and hence chemicals are being used for indoor
residual spray. Mosquito control is very necessary by
discovering new way to prevent its distribution by
using botanical extract. The first organ face the
botanical is the body wall or exoskeleton which it is very
rigid. The botanical extracts work in broken this power
by sequences changes gradually according to the time.
Figure 1 shows the that the effect of extract was
slightly appear after 6 hours by separating Ep from
cuticle; maybe because it is the first barrier faces the
extract from outside insect body, the Endocuticle and
Epidermis are not affected.
After 12 hours, the penetrate of extract material take it
way through the cuticle layers causing interruption of
structure form of it, and the spaces between the Ep and
Ex were increased (Figure 2). Because it is lethal to
mosquito larvae, which its body wall contact the
water, the activity is by cuticular contact. Al-Mehmadi
and Al-Khalaf (2010) also found activity by stomach
poisoning.
After 24 hours, the result shows the effective basement
membrane which was split from the epithelium
(Figure 3; Figure 4).
After 24 hours (Figure 5) the epidermis structure beginning
Figure 1 Treated larva cuticle after 6 hours
Note: Ep: Epicuticle, En: Endocuticle, EPD: Epidermis cells,
Bm: Basment membrane
Figure 2 After 12 hours of treating
Figure 3 After 24 hours of treating
Journal of Mosquito Research